Although seemingly distinct, these problems (a)-(c) represent a class of network interventions [1]} in which we benefit from identifying more central or highly connected individuals in the network.They belong to the class of “simple contagion” problems, which require only one rather than “complex contagion” that require multiple exposures [2]}, [3]}.
However, the challenge is that we do not have access to the relevant network structure. In application (a), having the Facebook network structure might not be useful, since the relevant network would be the physical contact network. In contrast, for application (b), finding a high degree node using a physical contact network of everyone who interacts with a physician is unlikely to be fully informative in characterizing her opinion leadership in the profession. For (c), and in epidemics like those analyzed in §, carrying out contact tracing for all individuals can be expensive in effort and time.
